Engineering Science and Materials Commons^™

Thermal Transient Analysis Of Mahogany Wood Biomass Pyrolysis: The Role Of Zeolite Catalyst Variations On Temperature Distribution, Yusri Yusri, Widya Wijayanti, Mega Nur Sasongko

Journal of Mechanical Engineering Science and Technology (JMEST)

Biomass pyrolysis is a thermochemical process that converts waste into fuel. The use of zeolite catalysts can enhance efficiency by accelerating biomass decomposition. To demonstrate its effect, thermal simulations were conducted using ANSYS Thermal Transient to analyze temperature distribution, reaction rates, and catalyst effectiveness in the pyrolysis process. This study aims to improve thermal efficiency and temperature uniformity by analyzing the effect of 10% and 20% zeolite mixtures on heat distribution and heating rates at input temperatures of 650 K, 750 K, and 850 K, using the 2D axial symmetry method. The simulation was performed under specific boundary conditions: input …

Response Surface Modelling And Multi-Objective Optimisation Of Asphalt Binder And Mixture Properties Modified With Reclaimed Automotive Lubricants And Waste Glass Bottle Powder, Nura Shehu Aliyu Yaro, Jacob Adedayo Adedeji, Luvuno Nkosinathi Jele, Nasir Khan, Aliyu Usman, Jacob Olumuyiwa Ikotun

Journal of Sustainable Construction Materials and Technologies

Large volumes of reclaimed automotive lubricant (RAL) and waste glass bottle powder (WGBP) are disposed of inappropriately, causing serious environmental concerns. Furthermore, the paradigm shift towards sustainability in the pavement industry has prompted academics to investigate alternatives to conventional materials. As a result, one possible approach is to use these waste products as alternative materials in the asphalt pavement sector. This study investigated the combined use of RAL and WGBP as complementary modifiers, extending beyond the conventional single-modifier approaches reported in previous studies. Thus, in this study, response surface methodology (RSM) was utilised to optimise and predict the synergistic effects …

Design Of Air-Entrained Concrete For Airport Pavements Through Local Aggregate Utilization: Performance Optimization And Economic Analysis, Li Wentao, Rizwan Qadir, Arslan Mushtaq, Hilal Khan, Kamran Jillani

Journal of Sustainable Construction Materials and Technologies

Airport pavement construction in developing countries faces critical challenges balancing international performance standards with economic constraints, while limited research exists on optimizing air-entrained concrete mixes using locally sourced materials for cost-effective solutions. This study investigated the development of economical air-entrained concrete mix designs for airport pavements utilizing Pakistani aggregates and systematic cement content optimization. Comprehensive experimental evaluation included material characterization through petrographic analysis, alkali-aggregate reactivity assessment via accelerated mortar bar testing, and mechanical property development across cement contents from 360-450 kg/m3. Air entrainment was achieved through controlled admixture dosing while maintaining target slump of 50mm. Results demonstrated that locally sourced …

Molybdenum-Doped Zinc Oxide Nanocomposite For Sustainable Photoelectrocatalytic Degradation Of Dyes And Antimicrobial Activity, Samar A. Salim

Nanotechnology Research Centre

Mo-doped ZnO nanocomposite was synthesized by using auto-combustion method. X-ray diffraction patterns of prepared nanocomposite indicated effective construction of crystalline Mo/ZnO NCs with co-existence of MoO2 and ZnO in required weight ratio. XRD results revealed also that ZnO crystallite size decreased as Mo-doping concentration increased. The direct band gap reduced from 3.309 eV of (MZ-0) to 3.258 eV of (MZ-5), demonstrating a negative correlation with Mo-doping levels. The electrocatalytic activity of Mo/ZnO NCs was assessed by their capability to degrade Indigo Carmine (IC) and Murexide (ME) dyes, and their antibacterial properties were also evaluated. The electrocatalytic (EC) degradation efficiencies for …

Additive Manufacturing Of Spatially Variant Actuating Structures From Shape Memory Polymers., Katia Lizbeth Delgado Ramos

Open Access Theses & Dissertations

This dissertation studies the structure-processing-function relationships of additively manufactured shape memory polymer blends, with emphasis on mechanical anisotropy. Chemical exposure, thermally activated recovery, self-healing behavior, and 4D printed functional response. Two polyester-based blends were studied: a binary blend composed of polycaprolactone and thermoplastic polyurethane (PCL/TPU) blend, and a ternary blend composed of polycaprolactone/thermoplastic polyurethane/ polylactic acid (PCL/TPU/PLA) blend. The materials were melt-compounded using a twin-extruder to produce filament for fused filament fabrication (FFF). Specimens were fabricated using four different raster orientations, 0°,90°, 0/90°, and 45°, to investigate the influence of processing architecture and composition on the mechanical performance, recovery behavior, …

An Approach To Incorporate Skid Resistance Into Balanced Asphalt Mix Design Framework, Sandeep Reddy Gottam

Open Access Theses & Dissertations

The Balanced Mix Design (BMD) process aims to achieve an economical blend of aggregates, binder, and additives for satisfactory performance against rutting and cracking-related distresses, compared to volumetric design methods. Although the BMD process improves the structural performance of pavements, functional performance is essential for the comfort and safety of road users. Road user comfort is influenced by pavement distresses, while road user safety is largely determined by the skid resistance (frictional resistance) of the pavement. The aim of this dissertation was to incorporate skid resistance into the BMD framework through an approach. To develop an approach that integrates with …

Influence Of Nickel Content On Microstructural Evolution And Densification Of Tungsten Fabricated Via Vat Photopolymerization, Jose Miguel Gonzalez

Open Access Theses & Dissertations

Hybrid additive manufacturing of tungsten-nickel alloys, combining vat photopolymerization (VPP) for patterning with custom thermo-hydrogen post-processing for reduction and densification, has emerged as a promising route for fabricating complex, high-resolution tungsten architectures. However, fabrication of tungsten via this hybrid AM technique remains challenging due to poor densification and significant defect formation during debinding and sintering. In this work, these limitations were addressed using nickel as a sintering aid in combination with controlled thermal processing conditions. Existing studies on activated sintering of tungsten typically focus on a single composition or sintering condition, limiting understanding of the combined effects of composition and …

First-Principles Study Of Uranium Mononitride, Roy Noe Herrera Navarro

Open Access Theses & Dissertations

This thesis presents a first-principles investigation of uranium mononitride (UN), withemphasis on the connection between uranium 5f electron correlation and defect stability. Electronic-structure calculations were performed within density functional theory using the Vienna Ab initio Simulation Package. Exchange-correlation effects were treated within the generalized gradient approximation, and a Hubbard correction was applied to the uranium 5f manifold. The adopted Hubbard parameter was motivated by first-principles linear-response analysis and considered in the broader context of DFT+DMFT descriptions of correlated uranium systems, including recent interpretations of UN as a Hund-metal system. Bulk UN was studied in unit-cell and 2 x 2 x …

Additively Manufactured Grx-810 Alloy: The Influence Of Build Interruptions Onmicrostructure, Tensile Strength And Fatigue Life., Javier Eduardo Lares Monarrez

Open Access Theses & Dissertations

This study investigates the influence of build interruption on the microstructure, microhardness, tensile behavior, and fatigue performance of laser powder-bed fusion (LP-BF) specimens in both the as-built and heat-treated conditions using the GRX-810 alloy. The heat treated condition incorporated Hot Isostatic Pressing (HIP), and both interrupted and uninterrupted samples were evaluated to isolate the effects of processing variables. Results indicate that build interruption did not produce significant changes in yield strength, ultimate tensile strength, or ductility, suggesting that the LP-BF process is robust enough to tolerate controlled interruptions without compromising bulk mechanical integrity. Microhardness measurements and microstructural observations further supported …

Additive Manufacturing Of Roman Concrete-Inspired Self-Healing Polyvinyl Alcohol-Polylactic Acid Blends: Influence Of Composition, Processing Temperature, And Raster Pattern On Print Quality And Mechanical Performance, Stephanie Moreno

Open Access Theses & Dissertations

This study investigates development of Roman concrete-inspired self-healing polymer blends based on polyvinyl alcohol (PVA) and polylactic acid (PLA) for the additive manufacturing (AM) process of fused filament fabrication (FFF). The motivation for this work stems from the need to enhance durability and functionality of biodegradable polymers while addressing environmental concerns associated with plastic waste. Inspired by the multifunctional and hierarchical architecture of Roman concrete. PVA is integrated as a hydrophilic, sacrificial phase similar to lime clasts, embedded inside a PLA-rich structural matrix to promote physical interaction and water-activated self-healing behavior. Binary PVA:PLA blends with ratios of 5:95, 10:90, 20:80 …

Versatile Exoskeleton Control Paradigms For Agile Human Locomotion: Task-Agnostic And Stability-Augmented Assistance, Miao Yu

All Dissertations

Lower-limb exoskeletons have shown great potential for assisting human locomotion, but designing controllers that provide assistance across diverse locomotor tasks and under external perturbations remains a major challenge. Many existing controllers for steady-state walking rely on pre-defined reference trajectories, which constrain voluntary human motion and limit adaptability across tasks. Moreover, they usually assume stable walking, while their performance under unstable conditions remains largely unexplored. In addition, existing gait stability augmentation controllers are often reactive rather than proactive to unstable conditions. In this dissertation, we propose control frameworks that preserve voluntary human motion while addressing two major challenges: providing task-agnostic assistance …

Porous Hydrophobic Adsorbent Coatings For Carbon Dioxide Capture, Samuel Babatunde Olushola

Theses and Dissertations

This work presents the development of a porous, hydrophobic zeolite 13X coating for the separation of carbon dioxide (CO₂) from flue gas or natural gas. Zeolite 13X was combined with yeast, glucose, and sodium alginate as pore-forming agents, and with polytetrafluoroethylene (PTFE) and Polydimethylsiloxane (PDMS) as hydrophobicity-inducing agents to enhance water resistance while maintaining CO₂ access to the adsorbent. The study explored PTFE/13X mass ratios ranging from 0 to 2.33 to investigate the interplay between hydrophobicity and CO₂ uptake. The wettability of the coating was characterized by using a temporal water contact angle (WCA) measurement. Increasing …

Molecular Catalysts For Electrochemical Nitrogen Activation Toward Sustainable Ammonia Synthesis, Jin-Xiu Han, Hao Xue, Xian-Biao Fu

Journal of Electrochemistry

Homogeneous electrocatalytic nitrogen reduction reaction (NRR) provides a powerful framework to interrogate molecular nitrogen-fixation pathways under mild conditions. By tuning the metal center, ligand architecture, and reaction medium, these systems enable capturing key intermediates and delivering mechanistic insight at the molecular-level resolution. Nevertheless, advances remain constrained by highly reduced operating potentials, intense competition from the hydrogen evolution reaction (HER), limited durability in turnover, and inadequate long-term stability.

In this review, we take electron delivery to the molecular active site as the guiding principle for organizing homogeneous electrochemical N₂ activation and transformation. We classify reported systems into direct electron transfer …

Water-Driven Solid Electrolyte Interphase Governs Continuous-Flow Ammonia Electrosynthesis, Peng-Bo Liu, Sheng-Liang Zhai, Ji Huang, Zhong-Shuo Zhang, Jie Zeng, Shao-Feng Li

Journal of Electrochemistry

Flow-cell architectures have emerged as a powerful platform for continuous and stable lithium-mediated nitrogen reduction (Li-NRR), enabling ambient-condition electrochemical ammonia synthesis and offering a promising alternative to Haber-Bosch processes. However, Li-NRR is exceptionally sensitive to trace water, and even minor variations in water content can profoundly alter interfacial chemistry. Here, we systematically investigate how initial water concentration affects Li-NRR performance in a continuous-flow cell. Excess water drives the formation of a thick solid electrolyte interphase (SEI) layer, which may impede nitrogen access to metallic lithium and hinder lithium-ion transport. As a result, the ammonia Faradaic efficiency collapses from ~61% to …

Insertion Of Noble Metal Free Cathodic Catalyst Layer With Fe-N-C Catalyst For Boosted Performance Of Pemfc, Shi Zhou, Muhammad Tariq, Asif Nadeem Tabish, Muhammad Salman, Fan-Di Ning, Muhammad Rayyan Tayyab, Ran-Ran Peng, Meng-Geng Hao, Wen-Mu Li, Xiao-Chun Zhou

Journal of Electrochemistry

Economical Fe-N-C catalysts are considered as promising alternatives to platinum group metal catalysts for proton exchange membrane fuel cells (PEMFCs). Despite exhibiting robust activity on rotating disk electrodes, their performance within membrane electrode assemblies often experiences limitations, such as decreased O₂ diffusion, high H₂O₂ formation, low proton conduction, and a lower electron transfer number. In this study, key factors, including proton transport, electron conduction, and gas diffusion within air-breathing PEMFCs, have been investigated by adjusting cathode catalyst layer (CCL) compositions. From the experimental results, the optimal peak power density was obtained when the loading of Fe-N-C …

Design And Fabrication Of A Composite Torpedo Baseball Bat, Peyton A. Lee, Carter Mathison, Jaden J. Schwantz, Noah Misukanis, Cole V. Stalberger

Research & Creative Achievement Day

Observing current trends in Major League Baseball, there has been increasing interest in torpedo-style wood bats due to their unique weight distribution. Unlike traditional bat geometries, the torpedo design shifts more weight toward the hands, improving balance and allowing for greater control throughout the swing. This project applies the same concept using composite materials so that high school and college players can also have access to this design innovation. The proposed bat is constructed from carbon fiber reinforced polymer with an epoxy resin to create a lightweight and durable structure. The design aims to maintain the performance benefits of the …

Comparison Of Pfas-Free Hydrophobic Layer-By-Layer Coatings For Cellulosic Textiles: Evaluation Of Water Repellency, Mechanical Durability, And The Effects Of Fabric Construction, Elvira Isenzhulova, Radika Bhaskar

School of Design and Engineering Papers

Environmentally safe water-repellent coatings are urgently needed for the textile industry as an alternative to PFAS-based finishes. Challenges include development of coatings that are effective in imparting both water repellency and mechanical durability, with relatively simple synthesis to promote industry use. This study compared the performance and abrasion resistance of two different bio-based, layer-by-layer (LbL) self-assembled hydrophobic coatings for cellulosic fibers. Textile samples were coated with bilayers composed of negatively charged plant-derived carnauba wax and a positively charged component: either poly-L-lysine or lower-cost zinc oxide nanoparticles. To investigate the influence of surface microroughness on coating adhesion and performance, two different …

Analysis Of Factors Enabling Organisational Governance Maturity For The Technical Audit Function In Tanzania, George C. Haule

Tanzania Journal of Engineering and Technology (TJET)

The study aimed to identify key factors contributing to Organisational Governance Maturity (OGM) of the Technical Audit Functions (TAF) in Tanzania.  The study employed a sequential approach as a research design.  The first step was to collect and analyse literature studies to identify factors enabling the OGM of the TAF.  Next, a questionnaire was administered to one hundred twenty-eight (128) respondents from seven (7) TAFs to rank the key enabling factors that were identified from the literature that influence the OGM of TAF in Tanzania.  Using data from a questionnaire administered to 128 respondents, a two-step strategy was employed to …

Complex Systems Mapping Of Fiscal Growth Dynamics At Strategic Maritime Chokepoints Using Time-Series Slopes, Rahul Balamurugan, Preethi Nanjundan, Avichal Sharma

Northeast Journal of Complex Systems (NEJCS)

This study examines how maritime and trading states allocate public resources between defence, health, and economic growth around three strategic chokepoints the Strait of Malacca, the Strait of Hormuz, and the Suez Canal. The analysis extends the classic “guns versus butter” framing by treating defence and health spending as co-evolving components of an interconnected fiscal-growth system. Using World Development Indicators data (1999-2024), trend slopes are estimated for military spending (% of GDP), healthcare spending (% of GDP), and GDP growth (annual %). Two derived indicators are computed, a defence-to-health slope ratio (military slope/health slope) and a fiscal-balance proxy (health slope …

Hybrid Thermosetting Polymer Nanocomposite Thin Films With Optimized Thermal Conductivity And Mechanical Reinforcement, Vinicius Alvarenga, Camila M. Maroneze, Matheus S. Dias, Bruno Milton Oliveira Silva, Jaime Taha-Tijerina, Christiano J. S. De Matos, Hélio Ribeiro

Informatics and Engineering Systems Faculty Publications

Epoxy-based thin films reinforced with graphene oxide (GO), hexagonal boron nitride (h-BN), and their hybrid combination (GO/h-BN) at low filler contents (<  1 wt%) were developed to advance thermosetting nanocomposites for high-performance thermal interface materials (TIMs). The incorporation of these 2D nanostructures led to marked and simultaneous increases in both the storage modulus (E′) and the glass transition temperature (Tg) for the individual and hybrid systems. These enhancements indicated strong interfacial interactions between the nanofillers and the epoxy matrix, promoting a more efficient crosslinking density and reinforcing the overall rigidity of the polymer network. Uniform thin films, processed under controlled conditions, exhibited efficient phonon transport without compromising their dielectric integrity, as demonstrated by steady-state and 3-ω thermal analyses. The incorporation of 0.5 wt% GO/h-BN resulted in up to …